Hi folks,

I have 2 rough '92 XJS's for parts, and would like to see if the ABS master cylinder can be tested.
The cars are too rough to drive on gravel and stomp on the brakes, so can it be tested somehow?
One of my friends in the Ontario Jag Club has a '94, and has had a brake failure. The dealer says master and accumulator.
The ball is available but not the master.
It's a lot of work to install a master, so I'd like to verify the used part if possible.
Thanks,
Rob

 

Rob,

The part you're referring to is the Actuation Unit, not a Master Cylinder. The master cylinder is merely the small front chamber at the front of the Actuation Unit. If your friend's dealer said the master cylinder had failed it perhaps indicates that he doesn't know much about this Teves system.

In my limited experience, the Actuation Unit doesn't tend to fail. I've never seen one that's definitely failed and I only know of one person who has rebuilt one.

There are other elements in the system that are much more prone to failure than the Actuation Unit - the Accumulator, the Pump and, more recently, specifically elements within the ABS valve block that is bolted to the side of the Actuation Unit. This fails for two reasons - Deterioration of the ribbon cable that actuates the valves - and micro-sediment that gets under the edges of the valves and prevents them closing. Either of these situations can have disastrous consequences.

If I were you and I wanted to get a degree of confidence in the system, I would do the following:

- Perform the blink test to see if any fault codes are being stored
- Undertake the 32 continuity tests
- Although partially covered by 3 of the continuity tests, you could also apply 12v to the individual ABS solenoid valves and check that they all click
- Remove the ABS valve block cover and visually inspect the ribbon cable and the general condition of the solenoid valves.

If all of the above is successful, I think you can have a reasonable degree of confidence that the Actuation is ok, but I certainly wouldn't guarantee it as a working used part if I was selling, it if you haven't driven the car and tried the brakes.

Good luck

Paul

 

Paul,
Thank you very much for your speedy and thorough reply.

I'll get busy on this and report.

Cheers,

Rob

 

Nice pics Rob - you certainly have a lot of jags! What is the plug lead hanging out of the front of the black XJS near the headlamp?
Good luck with the ABS.
LeeP

 

Lee,

That looks like the wiring plug for the pre-heater fitted in the lower hose on Canadian cars. . I fitted one of those a few years ago and run it off a 110v site transformer.

Paul